"""
MCP server exposing TOON conversion tools.
This server is designed to be run over stdio so that MCP-compatible hosts
(such as IDEs or orchestrators) can invoke it as a subprocess.
"""
from __future__ import annotations
import asyncio
from mcp.server import Server
from mcp.server.stdio import stdio_server
from .codec import json_to_toon, toon_to_json, system_prompt_to_toon
server = Server("toon-mcp-server")
@server.tool()
async def convert_json_to_toon(payload: object) -> str:
"""
Convert JSON-compatible data into TOON text.
Parameters
----------
payload:
Any JSON-serialisable structure (usually provided by the MCP host).
"""
try:
return json_to_toon(payload)
except (TypeError, ValueError) as exc:
# Tool error messages should be explicit so the MCP host can surface
# them directly to the user.
raise ValueError(f"convert_json_to_toon: {exc}") from exc
@server.tool()
async def convert_toon_to_json(toon_text: object):
"""
Convert TOON text back into JSON-compatible data.
Parameters
----------
toon_text:
String containing TOON-formatted data.
"""
try:
# The codec layer will validate that this is a string and raise
# a clear error if not.
return toon_to_json(toon_text) # type: ignore[arg-type]
except (TypeError, ValueError) as exc:
raise ValueError(f"convert_toon_to_json: {exc}") from exc
@server.tool()
async def convert_system_prompt_to_toon(prompt: object) -> str:
"""
Convert a plain system prompt string into TOON format.
Parameters
----------
prompt:
The system prompt text to be wrapped in a minimal TOON document.
"""
try:
return system_prompt_to_toon(prompt) # type: ignore[arg-type]
except TypeError as exc:
raise ValueError(f"convert_system_prompt_to_toon: {exc}") from exc
async def _run() -> None:
"""
Entry point used by :func:`main` and by the console script.
"""
async with stdio_server() as (read_stream, write_stream):
await server.run(read_stream, write_stream)
def main() -> None:
"""
Console-script entry point for ``toon-mcp-server``.
"""
asyncio.run(_run())
if __name__ == "__main__":
main()
